Tuberculosis (TB) (caused by Mycobacterium tuberculosis) kills nearly 3 million people each year making it the most lethal bacterial disease known. The emergence of multi-drug resistant strains of this bacterium has made the search for new treatments of TB of the utmost importance. A major factor contributing to the difficulty of treating TB and related diseases lies in the impermeability of the mycobacterial cell wall. Inhibition of biosynthesis of the cell wall would cause the mycobacteria causing TB and related diseases to be inviable. This may be accomplished by inhibition of the enzymes involved in cell wall biosynthesis with small molecules. The Kiessling group is currently studying a vital galactosyltransferase, GlfT, involved in the galactan biosynthesis of the mycobacterial cell wall. The exact function of GlfT is unknown, but recent results from the group appear to show that GlfT is a processive enzyme capable of making the polysaccharide portion of the cell wall with altering beta-(1-5) and beta-(1-6) linkages. The purpose of this proposal is to verify if GlfT can build the galactan chain of the mycobacterial cell wall in a processive manner and study the factors in the substrate that influence this proposed processivity. This goal will be accomplished through the use of chemical methods to synthesize suitable substrate templates for a distraction assay to test the processivity of GlfT. Portions of these substrates will be varied to study the affect of these changes on the function of GlfT. Finally, the most active substrate will be identified by chemical and biological methods. The results with the previously used substrate templates will then be verified with the natural substrate mimic. The studies outlined in this proposal should give valuable structural information laying a solid foundation for the design of potent inhibitors for GlfT, which might lead to new treatment methods for TB. Relevance - This proposal outlines experiments to study the enzyme GlfT that is essential to the biosynthesis of the cell wall of the mycobacterium that causes tuberculosis. This research should elucidate the exact function of GlfT, which could lead to the development of potent inhibitors for GlfT as new treatments for TB.